Circuit breaker for electric cigar lighter



Dec. 5, 1961 L. J. GAUDET CIRCUIT BREAKER FOR ELECTRIC CIGAR LIGHTER Filed Nov. 18, 1958 ,9? XMM ATTORNEYS United States Patent 3,012,120 CIRCUIT BREAKER FOR ELECTRIC CIGAR LIGHTER Lawrence J. Gaudet, Meriden, Conn, assignor, by mesne assignments, to American Machine & Foundry Company, New York, N.Y., a corporation of New Jersey Filed Nov. 18, 1958, Ser. No. 774,725 6 Claims. (Cl. 200-116) This invention relates to circuit breakers, and in particular to disposable circuit breakers adapted for use in combination with electric cigar lighters of the type commonly used in motor vehicles. The device of the present invention is particularly adapted for use in combination with a cigar lighter socket of the type illustrated in US. Patent 2,495,657, but is not limited to such combination.

A principal object of the present invention is to provide a simple and reliable low cost circuit breaker which may be readily applied to conventional electric cigar lighter sockets, and which may be readily removed and replaced by a new device when it has served its purpose of protecting the lighter against excessive heating, or of protecting the wire against electrical overload in the case of a short circuit in the lighter. Further objects will be in part evident and in part pointed out hereinafter.

The invention and the novel features thereof may best be made clear from the following description and the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a preferred embodiment of the invention;

FIGURE 2 is a sectional View of the device, illustrated in circuit with a conventional cigar lighter socket, and showing the device in closed circuit condition;

FIGURE 3 is a sectional view of the device corresponding to FIGURE 2, but showing the device in open circuit position;

FIGURE 4 is a perspective view, on enlarged scale, of the contact spring element of the device in association with one of the insulating disc closures;

FIGURE 5 is a perspective view, also on enlarged scale, of the bimetallic thermostatic latch element of the device, in association with the other insulating disc closure; and

FIGURE 6 is an elevational view, partly in section, of a modified construction adapted for use with a bayonet catch connector.

Referring to the drawings, in FIGURE 2 is shown the outline of a conventional cigar lighter socket 10, provided with the usual rearwardly extending stud '12 for electrical connection. As is well known, the forward end of the socket 10 is provided with a flange 14, adapted to abut the front surface of the instrument board (not shown) of an automobile, in which the socket may be mounted in conventional fashion. Detachably mounted on the socket stud 12 is a preferred embodiment of the disposable circuit breaker of the present invention, indicated generally as 16. The circuit breaker 16 carries a rearwardly extending stud 18, preferably corresponding in size and form to the socket stud 12, and similarly adapted for electrical connection. As shown, the terminal 20 of wire 22 may be positioned over the stud 18, and secured in place by the nut 24.

The circuit breaker 16 comprises a generally cylindrical metallic housing 26, closed at both ends by insulating discs 28 and 30. As shown in FIGURES 1, 4 and 5, each of the discs 28 and 30 is provided with a plurality of spaced peripheral notches 32, and the housing 26 at either end is provided with a plurality of corresponding fingers or tabs 34, adapted to fit within the respective disc notches. The tabs and notches serve to align the elements for assembly, which may be completed 3,012,120 Patented Dec. 5, 1961 ICC by bending the tab ends inwardly over the outer faces of the associated discs.

The forward disc closure 28, as shown in FIGURES 2 and 3, is centrally apertured at 36, and in said aperture is mounted an internally threaded bushing 38. The bushing 38 comprises a central section 40 terminating in shoulders 42 and 44, and end skirts 46 and "48 of reduced external diameter. The bushing is secured in the disc closure 28 by positioning it within the aperture 36 thereof, the aperture fitting closely about the end skirt 46 and against shoulder 42, and the end skirt may be rolled over the outer surface of the disc closure to permanently engage the elements. On the rearward end of the bushing 38 is mounted a bimetallic thermostatic latch element indicated generally as 50. As shown, the latch element 50 comprises a base end 52 which fits over the bushing skirt 48' and against the bushing shoulder 44, and is fixedly mounted on the bushing by rolling over the end skirt, in the manner previously described.

As illustrated in FIGURES 2, 3 and 5, the latch element 50 is sharply bent at 54, whereby the base end 52 is joined to a forwardly extending section 56, and reversely bent at 58, whereby the section 56 is joined to a free leg 60 which extends rearwardly a short distance beyond the base end 52. Adjacent its outer end, the leg 60 is sharply offset in radially inward direction to form a detent 62, from which extends the inclined guide lip 64.

The stud 18 comprises a threaded portion 70 at one end, a flange 72, and an extension 74 of reduced diameter. The rearward disc closure 30 is centrally apertured at 76, whereby it is adapted to fit over the stud extension 74 and against the flange 72. Mounted on the stud extension 74, immediately inside the disc closure 30, is a contact spring element indicated generally as 80. The contact spring is generally U-shaped, being formed into a base leg 82 and free leg 84. The stud 18, disc closure 30 and contact spring 80 may be assembled by positioning the disc closure and contact spring on the stud extension 74, the base leg 82 of the contact spring being appropriately apertured for such purpose, and then upsetting the outer end of the extension to form a head 86. Preferably, a contact washer 88 is interposed between the stud head 86 and the contact spring. The free leg 84 of the contact spring may be substantially annular, as illustrated in FIGURE 4, and centrally apertured at 90. The aperture 90 desirably is relatively large with respect to the stud head 86, to permit passage of a tool to form head 86 and to allow the leg 84 to fit over the stud head when in open circuit position.

The device is normally assembled in the open circuit position or relationship illustrated in FIGURE 3 of the drawings. As will be evident, the contact spring 80 and the latch element 50 must be operatively aligned, and this relationship may be readily attained in assembly by appropriate disposition of the disc closure notches 32 and the housing tabs 34. The rearward disc closure 30 is provided with a relatively small opening or passage 92, in alignment with the outer end of the free leg 84 of the contact spring element 80. The passage 92 permits the insertion of a small tool, by means of which the free leg 84 of the contact spring may be biased toward and into contact with the latch element 50. As will be understood, movement of the contact spring leg 84 in such direction causes its outer end to engage the inclined guide lip 64 of the latch element, whereby the latch element leg 60 is displaced outwardly, permitting the spring leg 84 to pass over and engage behind the detent 62 of the latch element. In such simple fashion, the device is placed in closed circuit position, illustrated in FIGURE 2, whereby current may flow from the terminal 20 through stud 18, contact spring 80, latch element 50, and bushing 38 to the socket stud 12.

The bimetallic thermostatic latchelement 50 is adapted, when heated, to warp outwardly toward the wall of the housing 26. Accordingly, if the latch element is sufficiently heated by heat conducted from the socket stud 12 or by excessive current passing therethrough, the leg 60 of the latch element will warp outwardly and disengage the contact spring 80 from its detent 62, permitting the contact spring to return to its unbiased position illustrated in FIGURES, thereby breaking the circuit through the device. It will be recognized that upon subsequent cooling of the latch element, its leg will return to normal position, but will not contact nor engage'the contact spring, so that in the event of malfunction, the circuit is permanently broken. Desirably, the circuit breaker is designed to open in from 40 to 55 seconds due to excessive heating, it a normally operating l2-vo1t lighter drawing in the neighborhood of 7 amperes is held continuously in circuit. lnthe event of malfunction of the associated cigar lighter, resulting in the passage of excessive current, the circuit breaker will function in about 7 seconds when passing amperes, and substantially instantaneously when passing 40 amperes. In such event, the latch element is heated primarily by its inherent electrical resistance. i

As previously indicated, the circuit breaker device is readily applied to conventional electric cigar lighter sockets. For example, instead of applying the terminal to the socket stud 12, the circuit breaker 16 may be engaged to the socket stud 12, and the terminal 20' applied to the circuit breaker stud 18. In the event the circuit breaker performs its protective function, uponthe determination and correction of the cause of the lighter malfunction, the circuit breaker may be readily removed and replaced by a new device. This requires only removal of the terminal 20 from the circuit breaker stud 18, removal of the circuit breaker from the socket stud 12, replacement of a new circuit breaker on the socket stud 12, and application of the terminal 20 to the new circuit breaker-stud. The replacement operation is obviously quick and simple. Alternatively, it will be recognized that the circuit breaker-may be restored to operative closed circuit condition, by removing the terminal 20 therefrom and inserting a small tool, nail, or the like, through the passage 92 in the rear disc closure 30, to engage the contact spring 80 and the latch element 50 in the manner previously described.

As illustrated in FEGURE 6, the portion 70 of the stud 18 may be unthreaded, and enclosed by a. connector sleeve 94, to provide a bayonet type electrical connection. Obviously, if the socket stud 12 is other than threaded, the bushing 38 of the circuit breaker may be appropriately altered for electrical connection therewith. I

it will thus be seen that there has been provided by this invention a device in which the various objects hereinbefore set forth, together with many practical advantages, are successfully achieved. As various possible embodiments may be made of the mechanical features of this invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

I claim:

1. A circuit breaker including: a housing; insulating disc closures mounted in opposite ends of said housing; a

4 stud mounted in one of said closures and extending outwardly therefrom, the outer end of said stud being adapted for electrical connection; a contact spring element disposed inside said housing and secured to the inner end of said'stud, the inner end of said stud being provided with ahead, said contact spring being substantially U-shaped with one leg of said spring being apertured and retained under said stud head; the other leg of saidspring being apertured in general alignment with the stud axis; an

internally threaded bushing mounted in the other of said closures and extending therethr'oughr-and a bimetallic thermostatic latch element disposed inside said housing and mounted on said bushing, said latch element being adapted to normally engage and retain said spring element in closed circuit relationship and to release said spring element when displaced by elevated temperature.

2. A circuit breaker as defined in claim 1, wherein the disc closure mounting said stud is apertured in general alignment with the outer end of the free leg of said contact spring.

3. A readily detachable circuit breaker element for electric cigar lighters comprising: a housing; insulating disc closures mounted in opposite ends of said housing; a stud mounted in one of said closures and extending outwardly therefrom, the outer end of said stud being adapted for electrical connection; a substantially U-shaped contact spring element disposed inside said housing and secured by one leg thereof to the inner end of said stud; means to detachably connect said circuit breaker in electrical contact with an electric cigar lighter assembly, said means including a bushing mounted in the other of said closures and'extending therethrough; a through bore in said bushing to receive a portion of an electric cigar lighter; and a bimetallic latch element disposed in said housing and mounted on said bushing, said latch element including a tree leg extending toward and aligned with the free leg of said contact spring and adapted to normally engage and retain said spring element leg in closed circuit relationship and to release said spring element leg when displaced by elevated temperature.

4. The device as defined in claim 3 wherein the disc closure mounting said stud is apertured in general alignment with the outer end of the free leg of said contact spring.

5. The device as defined in claim 3 wherein the inner end of said stud is provided with a head, one leg of said spring being apertured and retained under said stud head,

,the other leg of said spring being apertured in general alignment with the stud axis.

6. Thedevice as defined in claim 5 wherein the disc closure mounting said stud is apertured in general alignment with the outer end of the free leg of said contact spring. 7

References Cited in the file of this patent UNITED STATES PATENTS Ashton et al. Aug. 19, 1958. 

